[Effects of eye tracking stimulation on movement of body's center of gravity and head in elderly subjects].

This study was designed to investigate the effects of eye tracking stimulation on the movement of the body's center of gravity (CG) and the head in aged persons 60 years old and above. Twenty-three healthy aged subjects ranging from 60 to 79 years old and 10 healthy young subjects were asked to pursue a pendulously moving horizontal target when standing with the feet together. The frequencies of target movement were 0, 0.1, 0.25, 0.5, 0.75, 1.0 and 1.5 Hz. The results were as follows: 1) The body sway locus patterns increased significantly up to around 0.5 Hz of target movement. 2) The total lengths of the locus traced by CG movement and the head movement were larger than that of control subjects throughout the test runs. The aged subjects were also affected by eye tracking stimulation, and showed individual variations. 3) The ratio of the anteroposterior component to the lateral component of CG movement was higher in the elderly subjects than in the control subjects, while head movement was characteristically different. 4) The averaged divisional frequencies were calculated in the range between 0.0195 and 1 Hz. In the anteroposterior component, the averaged divisional frequencies of CG movement and head movement were significantly larger while watching the moving target than when watching a stationary target.